• Information Systems Review
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• v.24 no.1
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• pp.1-19
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• 2022

Social media-based communication has become crucial part of our personal and official lives. Therefore, it is no surprise that social media sentiment analysis has emerged an important way of detecting potential customers' sentiment trends for all kinds of companies. However, social media sentiment analysis suffers from huge number of sentiment features obtained in the process of conducting the sentiment analysis. In this sense, this study proposes a novel method by using Bayesian Network. In this model MBFS (Markov Blanket-based Feature Selection) is used to reduce the number of sentiment features. To show the validity of our proposed model, we utilized online review data from Yelp, a famous social media about restaurant, bars, beauty salons evaluation and recommendation. We used a number of benchmarking feature selection methods like correlation-based feature selection, information gain, and gain ratio. A number of machine learning classifiers were also used for our validation tasks, like TAN, NBN, Sons & Spouses BN (Bayesian Network), Augmented Markov Blanket. Furthermore, we conducted Bayesian Network-based what-if analysis to see how the knowledge map between target node and related explanatory nodes could yield meaningful glimpse into what is going on in sentiments underlying the target dataset.

• Korean Journal of Optics and Photonics
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• v.35 no.3
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• pp.107-114
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• 2024

In this study, the feasibility of using the covariance-matrix-adaptation-evolution-strategy (CMA-ES) algorithm in a multichannel coherent-beam-combining (CBC) system was experimentally verified. We constructed a multichannel CBC system utilizing a spatial light modulator (SLM) as a multichannel phase-modulator array, along with a coherent light source at 635 nm, implemented the stochastic-parallel-gradient-descent (SPGD) and CMA-ES algorithms on it, and compared their performances. In particular, we evaluated the characteristics of the CMA-ES and SPGD algorithms in the CBC system in both 16-channel rectangular and 19-channel honeycomb formats. The results of the evaluation showed that the performances of the two algorithms were similar on average, under the given conditions; However, it was verified that under the given conditions the CMA-ES algorithm was able to operate with more stable performance than the SPGD algorithm, as the former had less operational variation with the initial phase setting than the latter. It is emphasized that this study is the first proof-of-principle demonstration of the CMA-ES phase-control algorithm in a multichannel CBC system, to the best of our knowledge, and is expected to be useful for future experimental studies of the effects of additional channel-number increments, or external-phase-noise effects, in multichannel CBC systems based on the CMA-ES phase-control algorithm.

• Journal of The Korean Association For Science Education
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• v.26 no.2
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• pp.246-257
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• 2006

TIMSS (Trends in International Mathematics and Science Study) aims to produce reliable and internationally comparable indicators of student achievement. The TIMSS science achievement scale summarizes student performance on test items designed to measure a wide range of student knowledge and proficiency. This study analyzed Korean middle school students' science achievement at the advanced and high international benchmarks of the four benchmark levels of the benchmarks classified in TIMSS 2003 in light of science content areas (physics, chemistry, biology, earth science, and environmental science) and item characteristics. The average percent correct on items at the advanced benchmark by Korean students was highest in physics followed by earth science, biology, chemistry, and environmental science, whereas internationally the order was earth science, chemistry, biology, physics and lastly environmental science. Korean students performed relatively better in physics yet somewhat worse in chemistry than other top-performing countries. According to item analysis, Korean students reaching the advanced international benchmark understood some fundamentals of scientific investigation, but demonstrated weakness in written explanations of scientific principles, abstract science concept comprehension, and application of scientific concepts to solve quantitative problems. In addition, Korean students reaching the high international benchmark demonstrated relative weak conceptual understanding of ecology compared with other countries.

• Journal of The Korean Association For Science Education
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• v.26 no.4
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• pp.492-501
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• 2006

Gender differences in TIMSS 2003 science achievement by item type, benchmark, and content area were examined by producing a Gender Differences Index (GDI) in this study. International trends identified that male students performed better than female students in TIMSS 2003 science achievement in all types of items. The overall achievement of Korean male students was better than Korean female students, especially in multiple-choice type items. Male students outperformed females in three benchmarks, including advanced, high, and intermediate international benchmark, but they did not outperform females in the low international benchmark when gender differences of the international average as well as the Korean average were taken into account. The results of the analysis of the international average and the Korean average by content area showed that gender differences were the greatest in earth science and smallest in chemistry. In life science, female students excelled when considering the international average while male students excelled when considering the average of Korean students' performance. In addition, the number of items in which male students outperformed females was larger in both factual knowledge and the conceptual understanding domain. Implications for reducing gender differences in science achievement in Korea based on the results were provided.

• Journal of The Korean Association For Science Education
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• v.26 no.4
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• pp.475-491
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• 2006

In physics education, the research on students' conceptions has developed in the discussion on the nature and the difficulty of conceptual change. Recently, mental models have been a theoretical background in concrete arguments on "how students' conceptions are constructed or created." Mental models that integrate information in the presented problem and individual knowledge in their long-term memory have important information about not only expressed ideas but also in the thinking process behind the expressed ideas. The purpose of this study is to investigate the forming process and the characteristics of high school student's mental models about circular motion, and how they were changed by instruction. We used the think-aloud method based on the instrument for identifying student's mental models about circular motion, pretest of physics concept, mind map and interview for investigating student's characteristics. The results of the study showed that instructions based on the mental model theory facilitated scientific expressed model, but several factors that affected forming mental models like epistemological belief didn't change scientifically after 3 lessons.

• Journal of The Korean Association For Science Education
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• v.26 no.6
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• pp.675-690
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• 2006

This study investigated students' views in relation to a career in science as a first step towards developing science career education programs and materials. The instrument was developed through preliminary surveys. The questionnaire was sent to, administered and returned by 3608 students including 1036 primary, 1137 middle, and 1435 high school students, who were selected through stratified cluster sampling from all over the country. The results were analyzed using statistical package program. The students' image view of science, preference for science and science learning, perception of science achievement, career hope for oneself, degree of hope in getting science-related job, perception about science-related career, important factors of science career choice, and their hope for science/non-science career and the reason for their choice in the past and present were investigated. The results show that "science as an experimentation activity" was the most frequent image view of science. The preference for science and science learning was more positive than the perception of science achievement. The percentage of total students who want to have science career was 21%, and this percentage of middle school students was especially low. The most frequent answers for advantages of science career were 'useful for national development', 'possible to get new knowledge', and those for disadvantages were 'dangerous', and 'too much to study'. The most frequent reason for students' choice of a science career was 'interest in science and science learning'. Judging from these results, the basic direction for science career education should be in raising the students' preference for and interest in science learning. The positive awareness for a career in science and vision for a science job in the future should be given through a science career education and science career education proper to the students' developmental stage and characteristics is more important.

• Journal of The Korean Association For Science Education
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• v.29 no.5
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• pp.564-579
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• 2009

The purpose of this study was to examine the change in the classes of the beginning science teachers through a cooperative mentoring program that induces the practice of reflective thinking. Participants in this study included three mentor-teachers, two teachers in doctorate or masters courses, one university professor, and three mentee-teachers who had less than four years of teaching experience. We collected data such as video recordings of mentee-teachers' classes and transcription, lesson plans, recording of one-on-one mentoring and transcription, mentor's and mentee's journals, and RTOP class observation reports. RTOP was used for the class analysis, and the cognition and changes in mentee-teachers' classes were determined from their journal entries and one-on-one mentoring interview materials. According to mentee-teachers' recognition of changes in their classes during the mentoring program, they themselves recognized their teacher-centered teaching styles, misconception, and lack of content knowledge. Furthermore, there were changes in the mentee-teachers' classes through their reflective practice and improvement. Based on the result of this study, however, the teachers' reflection was not all accompanied with reflective practice even if the beginner science teachers made some partial changes in reflective practice by reflection. This means that it is hard to instill a reflective practice in mentee-teachers through mentoring in a short period. Therefore, we consider that more systematic and long-term mentoring is necessary for beginner science teachers.

• Journal of The Korean Association For Science Education
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• v.29 no.8
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• pp.934-950
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• 2009

This study attempts to identify the relationship between students' images of science and science learning, and their career choices. A total of 163 students (seventh graders) from three different middle schools participated in this study. Students' images of science and science learning were investigated using the Draw-A-Scientist Test (DAST) and the Draw-A-Science-Learner Test (DASLT), respectively. Then, students' drawings were analyzed using the Draw-A-Scientist Test Checklist (DAST-C) and the Draw-A-Science-Learner Test Checklist (DASLT-C). The relationship between each element composing the students' images and their career choices were analyzed. Among several elements constituting the students' image of science, 'expression,' 'lab coat,' 'oddity,' 'knowledge symbol,' 'technology symbol,' 'co-work,' 'danger,' and 'STS' showed significant differences between students who chose a science-related career and students who did not. It was also revealed that the following elements - 'expression,' 'learning type,' 'inquiry symbol,' and 'learning place' - were more significantly associated with a science-related career choice compared to other elements consisting of an image of science learning.

• Journal of The Korean Association For Science Education
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• v.29 no.5
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• pp.531-540
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• 2009

The purpose of this study is to investigate the meaning and process of scientific observation. Hence, this study reviewed and discussed meanings and process of scientific observation described in philosophy, the philosophy of science and science education. Major researches on scientific observation are focused on a characteristic and type of scientific observation behavior. These research can suggest what is the characteristic of observation facts generated by observer. But it cannot show what is the meaning and process of scientific observation, it should be provide to students. According to the result in this study, scientific observation is affected by observer's subjective factors, such as experience, background knowledge, interpretation(not inference) and observation skill. All factor are integrated as an intellectual framework, and it is able to be changed by the observed facts. On the other hand, inference is excluded on scientific observation, but it have constantly affect on intellectual framework through feedback. This study on scientific observation provides a scaffold in various activities of scientific observation to be provided to students.

• Journal of The Korean Association For Science Education
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• v.29 no.4
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• pp.463-476
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• 2009

The purpose of this research was to find out if the analogical role-playing class activity had an effect on the students' academic achievements on cellular respirations as well as their science learning motivation for those who took part in the cellular respiration. To examine the effects of applying the activity, the research was conducted targeting a high school with humanities and social sciences courses, located in Busan. The target was specified as two classes that had selected a Biology II class, with one class (27 students) set as the test group and the other class (28 students) set as the control group. The conclusion drawn from this research was as follows: First, it seemed that the analogical role-playing activity helped the students to take their own parts in cellular respiration and gave them an opportunity to explain the concepts through direct physical activities, enhancing their academic achievements. Second, it was concluded that as the students found confidence and relevance in scientific knowledge as well as obtained a sense of accomplishment, the analogical role-playing class activity increased their level of satisfaction and their science learning motives. Third, as a result of the interviews on the change of the concept, students expressed some dissatisfaction over the new concept, and thought of the analogical role-playing activity as an intelligible alternative. It appeared that the alternative was plausible and fruitful.